NOx reduction by sulfur tolerant coronal-catalytic apparatus and method

ABSTRACT

This invention presents an NO x  environment effective reduction apparatus comprising a sulfur tolerant coronal-catalyst such as high dielectric coronal-catalysts like glass wool, ceramic-glass wool or zirconium glass wool and method of use. In one embodiment the invention comprises an NO x  reduction apparatus of sulfur tolerant coronal-catalyst adapted and configured for hypercritical presentation to an NO x  bearing gas stream at a minimum of at least about 75 watts/cubic meter.

STATEMENT OF GOVERNMENTAL INTEREST

The U.S. Government has a paid-up license in this invention and theright in limited circumstances to require the patent owner to licenseothers on reasonable terms as provided in the terms of contract No.DE-AC22-87PC79852 awarded by the U.S. Department of Energy.

This application is a divisional application of copending U.S. Ser. No.07/555,561 filed Jul. 19, 1990 now U.S. Pat. No. 5,147,516.

FIELD OF THE INVENTION

This invention presents an NO_(x) environment effective reductionapparatus comprising a sulfur tolerant coronal-catalyst such as highdielectric coronal-catalysts like glass wool, ceramic-glass wool orzirconium glass wool and method of use. In one embodiment the inventioncomprises an NO_(x) reduction apparatus of sulfur tolerantcoronal-catalyst adapted and configured for hypercritical presentationto an NO_(x) bearing gas stream at a minimum of at least about 75watts/cubic meter.

BACKGROUND OF THE INVENTION

Millions of tons of nitrogen oxides, (denoted, generally herein as"NO_(x) "), are emitted into the atmosphere each year as a result ofhigh temperature combustion of fossil fuels. Nitrogen oxides have beencited as major contributors to acid rain, by some estimates being aboutone-third of the acid contribution. Thus global interest has beenfocused on development of practical apparatus and methods to reduce theentry of nitrogen oxides into the atmosphere.

Since the first part of this century, developmental efforts have beendirected to convert nitrogen oxides to the individual elemental diatoms,N₂ and O₂. Yet despite the lengthy search, no previous investigator hassucceeded in devising a large scale procedure that does not requireintroduction of an exogenous reducing agent such as NH₃, CH₄, or CO.Alternatively, the use of electron beam (e-beam) irradiation, electricaldischarge irradiation, and light (laser or flash) has beenunsuccessfully attempted.

Previous investigation on chemical reactions in electrical dischargeincludes the work of Joshi in the 1920s (NO₂ and N₂ Odecomposition/electron movement between glass walls in AC discharge),Visvanathan in the 1950s (NO decomposition in electric charge). Otherslooking at the general conditions of electric/chemical reactions includeBrewer and Westhaver (J. of Phys. Chem.; 33:883 (1929)), Lacoste, G. andBess, R. (Rev. Chim. Minerale; 11:14 (1974), Bess, R. (Rev. Phys. Appl.;12:1029 (1977)). A more comprehensive presentation of the previous workin nitrogen oxide control is presented in A Unified Projection of thePerformance and Economics of Radiation-Initiated NO_(x) /SO_(x) EmissionControl Technologies, Person et al. Dept. of Energy Cpontract No.DE-AC22-84PC70259 (1985), the teachings of which are incorporated hereinby reference.

Other works on electro-catalysts take a position directly opposite fromthe instant invention. Such are those of van den Bleek, et al., (I.Chem. E. Symposium Series, U. of Salford (1979) stating that efficiencyof nitrogen oxide reduction is improved when catalytic surfaces are ableto donate an electron to the oxide, and Wooten and Mangold (U.S. Pat.No. 3,562,127 (1971)) (using gold plated, i.e. conductive, metal wool)and reporting augmented nitrogen reduction only when gold is used.

The instant inventive apparatus and method overcomes the problemspreviously encountered in the art. This invention employs a novelconcept based on recognizing chemical reactions occurring in gaseouselectrical discharge as distinct from reactions that result when equallyenergetic electrons are made to travel on metal surfaces.

SUMMARY OF THE INVENTION

This invention concerns an NO_(x) environment effective reductionapparatus comprising a sulfur tolerant coronal-catalyst. In oneembodiment the coronal-catalyst is a high dielectric catalyst, such asglass wool or ceramic-glass wool. A useful high dielectric material isstrontium titanate. In a particular embodiment the coronal-catalyst isTiO₂ (such as Rutile) in filamentous form. In a specific embodiment thecoronal-catalyst is charged at from at least about 75 watts/meter³.

Filamentous form (particularly bulk fibers about 1/16 inch in length)high dielectric catalysts comprises titanate (such as barium, calcium orzinc titanate), alumina, zirconia (such as ZrO₂) or magnesia.

In another embodiment this invention includes an NO_(x) environmenteffective reduction apparatus comprising a sulfur tolerantcoronal-catalyst wherein said coronal-catalyst is adapted and configuredfor hypercritical presentation to an NO_(x) bearing gas stream at leastabout 75 watts/meter³. In a particular embodiment the coronal-catalystis a high dielectric catalyst, such as glass wool or ceramic-glass wool.

One specific embodiment of the invention is an NO_(x) environmenteffective reduction apparatus comprising a sulfur tolerantcoronal-catalyst of glass wool or ceramic-glass wool;

said coronal-catalyst maintainable at at least about 75 watts/meter³ ;

coronal-catalyst is disposed in from one to a plurality of tubularmembers configured and adapted to receive a flow of NO_(x) bearing gas;

said coronal-catalyst being present in amounts of from about 0.5 toabout 150 kg/m³ ;

said apparatus activatable by voltage from about 4000 to about 30,000volts;

said voltage having a frequency of from 60 Hz to about 30,000 Hz;

said flow of NO_(x) bearing gas having a residence time in said tubularmembers of from about 0.2 to about 5 seconds or more. The usefulvoltages may have wave form of sine, square, triangle or pulse.

The invention further comprises a method of environment effectivereducing of NO_(x) emission comprising the step of exposing NO_(x) to asulfur tolerant coronal-catalyst at least about 75 watts/meter³. Inembodiments of the method the coronal-catalyst is a high dielectriccatalyst, such as glass wool or ceramic-glass wool.

One specific embodiment is a method of environment effective reducing ofNO_(x) emission comprising the step of exposing NO_(x) to a sulfurtolerant coronal-catalyst wherein said coronal-catalyst is adapted andconfigured for hypercritical presentation to an No_(x) bearing gasstream at a minimum of at least about 75 watts/meter³, optionallywherein the coronal-catalyst is a high dielectric catalyst, such asglass wool or ceramic-glass wool. This method, in one embodiment,comprises an NO_(x) environment effective reduction apparatus comprisinga sulfur tolerant coronal-catalyst of glass wool or ceramic-glass wool;

disposing said coronal-catalyst in from one to a plurality of tubularmembers configured and adapted to receive a flow of NO_(x) bearing gas;

maintaining said coronal-catalyst at at least about 75 watts/meter³ ;

said coronal-catalyst being present in amounts of from about 0.5 toabout 150 kg/m³ ;

applying voltage to said apparatus activatable by voltage from about4000 to about 30,000 volts;

said voltage having a frequency of from 60 Hz to about 30,000 Hz;

maintaining residency of said flow of NO_(x) bearing gas in said tubularmembers of from about 0.2 to about 5 seconds or more. The usefulvoltages may have wave form of sine, square, triangle or pulse.Alternating voltage is a useful embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphic representation of the surprising superiority of thecoronal-catalyst of the present invention as compared to noncoronal-catalyst column packing materials.

FIG. 2 is a schematic diagram of an experimental apparatus.

FIG. 3 is a graphic representation of sulfur tolerant coronal-catalystcompared to sulfur intolerant coronal-catalyst or sulfur intolerantcatalyst in general.

FIG. 4 is a schematic diagram of an coronal-catalytic column scrubber ofthe instant invention in industrial configuration.

FIG. 4a is a detail of a reactor tube of FIG. 4.

FIG. 4b is a cutaway view of a reactor tube of FIG. 4.

FIG. 5 is a schematic representation of coronal-catalyst reaction.

FIG. 6 is a graphic presentantion of the effect or a reducing gas on NOreduction.

DETAILED DESCRIPTION OF THE INVENTION

The instant invention is most clearly understood with reference to thefollowing definitions. "Sulfur tolerant" shall mean not more that about10% reduction in efficiency under conditions of either (i) 40 ppmsulfur/gm of catalyst, or (ii) a molar ratio of NO to SO₂ equal to orless than about 1.

"High Dielectric" refers to a dielectric constant approximately of glasswool and ceramic-glass wool--about 4--up to TiO₂ or ZrO₂ of 80 orbeyond.

"Coronal-catalyst" shall mean those catalysts which are notsubstantially surface area dependent as to catalytic activity. Aparticular coronal-catalyst is material such as glass wool, filamentousin nature, which disperses electron charge and channels the flow ofelectrons through a gas thereby enhancing electron density in the flowpath. Thus, such charge dispersion and electron channeling augmentselectron-molecule collision as compared to molecular-molecularcollision. This is represented in FIG. 5. Electron flow channeled and athigh velocity and density across coronal-catalyst surface is seen toincrease likelihood of an NO_(x) reduction producing collision.

"Environment effective" shall mean reduction of NO_(x) by at least about90% and preferably by about 98% and more preferably about 99.4%.

Kaowool is a trademark of Thermal Ceramics, Inc. (Augusta, Ga.) forceramic glass fibers and is generically referred to herein asceramic-glass wool.

NO_(x) shall mean any oxide of nitrogen, including but not limited toNO, N₂ O, NO₂, N₂ O₅, N₂ O₃, NO₃.

"Hypercritical presentation" to an NO_(x) bearing gas stream shall meanat a minimum of at least about 75 w/m³. Presentation parametersproviding hypercritical presentation include:

1. Operation from about 60° F. to about 1000° F. Preheating is notrequired.

2. Water vapor present in the reaction area up to about 12%.

3. SO₂ concentration up to about 3000 ppm/

4. Oxygen up to about 5%.

5. Voltage from about 4000 to about 30,000 volts. In particular it isobserved that rate of change in voltage going from about zero to a levelup to maximum augments efficiency. In various applications known waveforms such as sine, square, triangle and pulse as well as others areuseful.

6. Column packing from about 0.5 to about 150 kg/m³.

7. Column residence time from about 0.2 to about 5 seconds or more.Residence time is directly related to column flow and column length.

8. CO concentration up to about 1000 ppm. CO increases NO_(x) reductionas shown in FIG. 6.

9. Frequency of from 60 Hz to about 30,000 Hz.

Hypercritical reaction conditions are easily determined empirically. IfNO_(x) is not being effectively removed, removal is increased byincreasing voltage, increasing column packing, increasing residencetime, increasing temperature, increasing the frequency, decreasing O₂,decreasing SO₂, decreasing but not eliminating CO, or decreasing H₂ O.In instances of a slight excess of oxygen, addition of a reducing gassuch as CO will effectively reduce the adverse consequence of the oxygenexcess. Hypercritical presentation also recognizes that there is athreshold voltage below which no substantial NO_(x) reduction willoccur. Upon reaching the threshold voltage some variability in reductionis observed during an eguilibration or ignition phase of the reductionreaction. ##EQU1##

Without being bound by any particular theory, it is believed that thecoronal-catalytic reduction phenomenon is based on energy input ofcorona catalyzed reactions. A corona is an energetic electric field inwhich there is a cool discharge promoting the free flow of electronsthrough the inter-electrode spaces. It is important to distinguish thecool discharge herein employed from hot discharge. Cool discharge isdistinguished in (1) only the electrons gain appreciable energy throughthe system and therefor increased temperature, leaving the bulk ofmaterial flowing through the system largely substantially unheated andthus exiting at the approximate entry temperature, and (2) a corona isgenerally an evenly distributed discharge over the entire reactorvolume, where as a hot discharge is typically a local point to point arcengaging very little volume.

FIG. 5 depicts the hypothetical steps of coronal catalyzed reaction. InFIG. 5(a) the active corona is shown as free electrons flowing betweenthe negative and positive electrodes. The oxide of nitrogen used in thisexample is nitric oxide (NO), but other oxides of nitrogen are similarlyreacted. As the nitric oxide (NO) flows through the reactor it isbombarded by the free flowing electrons. Most of the electrons haveinsufficient energy to be incorporated into the nitric oxide electronorbitals. However, some electron collisions are sufficiently energeticfor electron incorporation as shown in 5(b). The unstable anionic nitricoxide molecule decomposes into a negatively charged nitrogen radical andan oxygen atom as shown in 5(c). Finally the nitrogen and oxygen atomsreact through other short lived intermediate reactions forming molecularnitrogen and oxygen as in 5(d).

FIG. 1 shows the surprising superiority of ceramic-glass wool and glasswool to conductive wools in reducing nitrogen oxides under electricaldischarge conditions. Glass wool is available from a number of sourcesincluding Fisher Scientific Company (Pittsburgh, Pa.) and Supelco, Inc.(Belle Fonte, Pa.). Examples of inferior materials shown in FIG. 1 aregold plated stainless steel stainless steel wool and steel wool none ofwhich achieved grater than 80% conversion of nitrogen oxides compared tosubstantially 100 percent conversion for ceramic-glass wool and glasswool when presented with up to about 700 ppm NO or more. The reactionconditions resulting in the data of FIG. 1 in which test gases werepassed over packing materials in a column were as follows:

NO concentration at inlet=490 to 500 ppm

N₂ balance to make 100%

Voltage across electrodes=0-18.0 KVAC

Residence time of gas in column=2.0 to 2.1 sec

Temperature of gas and column=30° C.

A test apparatus for determining NO_(x) removal is schematicallyrepresented in FIG. 2. Gas cylinders supply metered amount of gas to atest column, the gas and amount supplied depending on experimentalprotocol. Gas cylinder 2 supplies nitric oxide, gas cylinder 4 suppliesnitrogen, gas cylinder 6 supplies sulfur dioxide, gas cylinder 8supplies oxygen, and gas cylinder 10 supplies carbon dioxide. All gascylinders were metered by calibrated mass flow meters 12. The gaseousmixture from the cylinders is passed through a preheat section 14 priorto entering the furnace 16. Provision was made to humidify nitrogen gasprior to furnace entry by passage through a humidifying means 18, here abubbling device. Inlet of gas to the furnace was through a 1 inchdiameter tube 20, in this apparatus fashioned of a glass, high siliconeglass or ceramic insulator (e.g., Vycor™, Corning Glass Works, TroyN.Y.). Furnace 16 was 3 feet in length in the test apparatus but inpractice a furnace may be omitted or may be up to 10 ft. or longer.Within the furnace was packing material 22 such as glass wool (includingsilanized glass wool), polymeric fibers, ceramic-glass wool or metalwool being tested for coronal-catalytic properties. Packing material wascontained by packing supports 24. The packing material was served by apower supply 26 leading through line 32 to the packing material with anouter electrode 28 and an inner electrode 30 leading to the power supplythrough line 34 equipped with resistor 36. The apparatus was alsoprovided with a bypass line 38 having a valve 40 joining outlet samplingline 42 providing for inlet and outlet NO and NO_(x) determinations atthe same conditions, i.e. with the valve taking the place of thereactor.

FIG. 3 graphically represents the effect of SO₂ in inlet gas on NOconversion using glass wool catalyst packing. At 23° C. and NO input of500 ppm, O₂ input 0.011% H₂ O input 0.15% with a residence time of 2.0to 2.1 sec. Line A shows NO conversion without SO₂ present and line Bwith SO₂ at 470 ppm. No conversion remains substantially 100%.

FIG. 4 shows a diagram of a commercial application in a residentialsetting for the invention. NO_(x) reducing apparatus (400) has flue gas(402) enters the reactor (406) through plenum (404). The reactor asdepicted is of 230 tubes 24 inches long in a 60° pitch. In the plenumthe flue gas flow is directed to reactor tubes (408) being highdielectrics which are disposed, in this embodiment, in parallel. Eachtube (shown in detail in FIG. 4a) comprises an inner electrode (414) andan outer electrode (410) the tube being filled with coronal-catalyst(412) as packaging material. Energizing both electrodes may be by meansof a midpoint ground transformer. Packing density from about 1 to 5kg/m³ was used though about 0.5 to about 150 kg/³ is possible.

The flue gas traversing the interior of reactor tube (408) recombines asa single exit stream (416) in outlet plenum (418) and exits throughoutlet (420)l The voltage across the electrodes is supplied atfrequencies from about 60 Hz to about 30,000 Hz and in various waveforms. Voltage may be applied by energizing one or both electrodes.Energizing one electrode may be by means of a cold cathode transformer.

The complete system of FIG. 4 further comprises I.D. exhaust fan (422)and a power supply (428) powers fans and electric potential of thecoronal-catalyst and a tuning circuit (426), connected to the outletpower supply and capable of minimizing the power requirement of thepower supply. The source of NO_(x) emission as depicted is a homeheating system (424). In a typical residential application the overallsystem is about 5 to 6 feet in height and about one foot long on eachside. Large capacity is easily accommodated by such design modificationas including additional coronal-catalyst sections (406). Powerconsumption is about 150-300 watts in a residential furnace.

FIG. 6 illustrates the advantage to NO reduction in the presence of areducing gas such as CO. The percentage of NO reduction is plottedagainst voltage with CO at 750 ppm and NO at 500 ppm. CO (+) as comparedto no CO () discloses an increase in efficiency at a given voltage whena reducing gas is present in suitable quantity to increase NO reduction.

The operational utility of the instant invention is clear from thefollowing tables. Table 1(a) shows the reduction of NOin of 500 ppm withan O₂ content of 0.011% and a water content of 0.14% withoutcoronal-catalyst, with a distance between electrodes 10.8 mm, and aresidence time of 2.0 seconds. All percents are vol/vol unless otherwisenoted. The percentage of conversion and reduction is seen to increasewith voltage.

This invention will be better understood with reference to the followingtables disclosing data gathered utilizing the test apparatus of FIG. 2.

Table 1(b) shows the reduction of NOin of 500 ppm with an O₂ content of0.010% and a water content of 0.12%, using 15.0 gm ceramic-glasscoronal-catalyst, with a distance between electrodes of 10.8 mm, and aresidence time of 2.0 seconds. At voltages equivalent to (a) theefficience is seen as 2 to 3 times greater, and environment effective.

Table 1(c) shows the reduction of NOin of 500 ppm with an O₂ content of0.011% and a water content of 0.10%, using 9.2 gm of cotton as packing,with a distance between electrodes of 10.8 mm, and a residence time of2.0 seconds. At voltages equivalent to (a) the efficience is seen asabout 1/2 that of the coronal-catalyst of 1(b).

Table 2(a) shows the reduction of NOin of 500 ppm with an O₂ content of0.012% and a water content of 0.15%, using 7.68 gm glasscoronal-catalyst, with a distance between electrodes of 10.8 mm, and aresidence time of 2.1 seconds. At voltages from 6.1 to 16.04 kV. Theefficience is environment effective being over 90% at 16.04 kV.

Table 2(b) shows the reduction of NOin of 490 ppm with an O₂ content of0.013% and a water content of 0.16%, using 55.0 gm of Linde MolecularSeries 4A (Union Carbide, Danbury, Conn.), with a distance betweenelectrodes of 10.8 mm, and a residence time of 2.0 seconds. At voltagesequivalent to (a) the efficience is seen as about 10% less as comparedto the coronal-catalyst glass wool catalyst of Table 2(a).

Table 2(c) shows the reduction of NOin of 500 ppm with an O₂ content of0.017% and a water content of 0.15%, using 7.71 gm of silanized glasswool coronal-catalyst thus chemically modified, with a distance betweenelectrodes of 10.8 mm, and a residence time of 2.0 seconds. At voltagesequivalent to (a) the efficiency is seen to be well over 99%, clearlyenvironment effective.

Table 3(a) shows the reduction of NOin of 500 ppm with an O₂ content of0.02% and a water content of 0.18%, using 7.78 gm of zirconium coatedceramic-glass coronal-catalyst, with a distance between electrodes of10.8 mm, and a residence time of 2.0 seconds. At voltages up to about 16kV the efficiency is seen as close to 99%, being clearly environmenteffective.

Tables 3(b) shows the reduction of NOin of 500 ppm with an O₂ content of0.012% and a water content of 0.22%, using 7.79 gm of glass woolcoronal-catalyst, with a distance between electrodes of 10.8 mm, and aresidence time of 2.0 seconds. At voltages up to about 16 kV efficiencyis seen to be well over 99%, being clearly environment effective.

Table 4(a), (b) and (c), 5(a), (b), and (c) and (d) disclose moreexamples of glass wool as an highly effective coronal-catalyst.

Experiment 1

Using the above noted test apparatus metal wool (steel or stainlesssteel) was packed into the reactor. NO at about 500 ppm was introducedin a nitrogen stream into the reactor. The voltage was increased fromzero to approximately 18,000 vac during the test. Measurable NOreduction began at a voltage of 4,000 volts. NO reduction increaseduniformly and predictably with increasing voltages. A maximum reductionof about 60% occured at a voltage of 18,000 vac (the maximum possiblefrom the experimental equipment). Stainless steel wool performedsomewhat better than the steel wool but did not approach the efficiencyof coronal-catalyst of the invention.

Experiment 2

Gold, known to be a highly catalytic material under these conditions,was tested for NO_(x) reduction capability. The gold was plated on tostainless steel wool. Using the above noted test apparatus, the reactorthen supplied a NO/nitrogen stream and the voltage increased from zeroto about 18,000 vac. The gold system increased the NO conversion onlyslightly over unplated stainless steel wool.

Experiment 3

Using the above noted test apparatus, glass wool exhibited NO reductionin the test apparatus above a voltage of 6,000 vac. As the voltage wasincreased to above the hypercritical minimum the NO reduction wentthrough an unpredictable "ignition" stage at such threshold after whichthe NO reduction in this configuration significantly out performed themetal wool systems. 100 percent reduction occured at a voltage of about18,000 vac.

Experiment 4

Using the above noted test apparatus, Kaowool, above about 8,000 vac,the reduction of NO increased rapidly for increasing voltage, outperforming the glass wool tests of Experiment 3. 100 percent conversionoccured at a voltage of about 14,000 vac.

Experiment 5

The differences between Experiment 1 and 2 and Experiment 3 and 4 is theuse of a coronal-catalyst high dielectric material as opposed to aconductive material. Since gas is also a dielectric, a test with nopacking was run. After threshold voltage was reached, a maximumreduction of about 40 percent was observed.

                  TABLE 1                                                         ______________________________________                                        V(kv)          % Conv   % Red                                                 ______________________________________                                        1a. Empty Bed   d = 10.8 mm r = 2.05                                              NOin - 500 ppm                                                                            O.sup.2 in = 0.011%                                                                       H.sub.2 Oin = 0.14%                               8.16           0        0                                                     9.02           1.0      1.0                                                   10.04          1.0      1.0                                                   10.28          13.0     8.0                                                   14.02          29.0     18.0                                                  15.96          32.0     26.0                                                  1b. 15.0 gm ceramic-glass wool                                                                      d = 10.8 mm                                                                              r = 2.0                                          NOin - 500 ppm    O.sub.2 - 010%                                                                           H.sub.2 O = 0.12%                            8.00           0        0                                                     10.04          8.0      6.0                                                   12.04          62.0     58.0                                                  13.40          92.0     89.6                                                  1c. 9.2 gm Cotton                                                                             d = 10.8 mm                                                                              r = 2.0                                                NOin - 500 ppm                                                                            O.sup.2 = .011%                                                                          H.sub.2 O = 0.10%                                  8.12           0        0                                                     10.02          2.0      1.0                                                   12.04          38.0     32.0                                                  12.80          56.0     50.0                                                  13.0           62.0     56.0                                                  ______________________________________                                         Note that d = distance between electrodes and r = residence time in colum     in seconds.                                                              

                  TABLE 2                                                         ______________________________________                                        V(kv)          % Conv   % Red                                                 ______________________________________                                        2a. 7.68 g Glass wool                                                                          d = 10.8 mm                                                                              r = 2.1                                               NOin - 500 ppm                                                                             O.sup.2 in - 0.012%                                                                      H.sub.2 O = 0.15%                                 6.10           0        0                                                     7.94           1.0      1.0                                                   9.04           4.0      4.0                                                   10.00          33.0     19.0                                                  10.04          71.0     63.0                                                  14.06          87.6     85.6                                                  16.04          96.0     95.2                                                  2b. 55.2 gm Linde Molecular Series 4A                                                                  d = 10.8 mm                                                                              r = 2.0                                   NOin = 490 ppm O.sup.2 in = .013%                                                                         H.sub.2 O in = 0.16%                              6.04           0        0                                                     8.02           2.0      0                                                     10.02          34.7     34.7                                                  12.00          72.4     70.4                                                  14.02          80.6     76.6                                                  16.12          81.6     79.6                                                  2c. 7.71 gm Silanized Glass Wool                                                                     d = 10.8 mm                                                                              r = 2.03                                    NOin = 500 ppm    O.sup.2 in = .017%                                                                        H.sub.2 O = 15%                                 6.20           0        0                                                     8.04 0         0        0                                                     10.16          10.0     8.0                                                   12.12          60.0     54.0                                                  14.08          98.9     98.3                                                  15.02          99.9     99.8                                                  ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        V(kv)          % Conv.  % Red                                                 ______________________________________                                        3a. 7.78 gm Ziconium ceramic-glass wool                                                                 d = 10.8 r = 2.0 s                                  NOin - 500 ppm                                                                              O.sup.2p = 0.02%                                                                            H.sub.2 O = 0.18%                                 8.04           0        0                                                     10.10          3.0      3.0                                                   12.02          50.0     44.0                                                  14.02          85.0     82.0                                                  16.09          99.2     98.4                                                  3b. 7.79 gm Glass Wool                                                                          d = 10.8   r = 2.20                                             NOin - 500 ppm                                                                              O.sup.2 = 0.012%                                                                         H.sub.2 O = 0.22%                                8.02           5.0      5.0                                                   10.10          38.0     37.0                                                  12.06          80.0     74.0                                                  14.06          98.4     93.0                                                  16.02          99.8     96.0                                                  ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                        V(kv)          % Conv.  % Red                                                 ______________________________________                                        4a. 3.72 gm Glass Wool                                                                          d = 10.8   r = 2.0                                              NOin - 500 ppm                                                                              O.sup.2 0.10%                                                                            H.sub.2 O = 0.15%                                6.12           0        0.0                                                   8.02           3.0      2.0                                                   10.00          13.0     10.0                                                  12.06          48.0     46.0                                                  14.06          71.2     67.0                                                  16.06          82.0     67.0                                                  4b. 12.5 gm Glass Wool                                                                          d = 10.8 mm                                                                              r = 2.0                                              NOin = 490 pp O.sup.2 = .012%                                                                          H.sub.2 O = 0.13%                                6.12           2.0      2.0                                                   8.00           9.2      7.1                                                   10.02          27.6     24.5                                                  12.08          64.3     61.2                                                  14.00          89.6     88.4                                                  16.08          99.0     98.8                                                  17.08          99.6     99.4                                                  4c. 24.6 gm Glass Wool                                                                          d = 10.8 mm                                                                              r = 2.0                                              NOin - 500 ppm                                                                              O.sup.2 = 0.013%                                                                         H.sub.2 O = 0.15%                                7.98           3.0      3.0                                                   10.10          50.0     57.0                                                  12.00          90.0     88.0                                                  14.10          98.9     99.9                                                  ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        V(kv)          % Conv.  % Red                                                 ______________________________________                                        5a. 12.5 gm Glass Wool                                                                          d = 10.8 mm                                                                              r = 2.1                                              NOin - 200 ppm                                                                              O.sup.2 = 0.009%                                                                         H.sub.2 O = 0.14%                                6.02           9.5      7.5                                                   8.10           20.5     17.5                                                  10.08          53.0     49.5                                                  10.04          94.0     93.0                                                  14.00          99.8     99.8                                                  5b. 12.5 gm Glass Wool                                                                          d = 10.8 mm                                                                              r = 2.0                                              NOin 695 ppm  O.sup.2 = .011%                                                                          H.sub.2 O = 0.15%                                6.08           2.2      2.2                                                   8.00           6.5      5.0                                                   10.08          20.01    17.3                                                  12.08          51.1     45.3                                                  14.06          77.0     74.1                                                  16.6           90.5     89.2                                                  5c. 24 gm Lg Glass Wool                                                                          d = 10.8 pm                                                                              r = 1.9                                             NOin = 200 ppm O.sup.2 = 0.010%                                                                         H.sub.2 O = 0.15%                               6.10           0        0                                                     8.10           2.5      2.5                                                   10.08          14.0     12.5                                                  12.02          99.0     98.4                                                  12.56          99.8     99.8                                                  5d. 24.6 g Glass Wool                                                                           d = 10.8 mm r = 1.9                                             NOin 700 ppm  O.sup.2 in = 0.014%                                                                       H.sub.2 O = 0.15%                               6.12           0        0                                                     8.08           0.7      0.7                                                   10.02          10.0     8.6                                                   12.00          58.6     54.3                                                  14.02          92.1     90.0                                                  15.82          99.9     99.6                                                  ______________________________________                                    

We claim:
 1. A method of environment effective reducing of NO_(x)emission comprising the step of reactively exposing NO_(x) to a sulfurtolerant coronal-catalyst, said coronal-catalyst in filamentous form,and said exposure occuring at an electric density of at least about 75watts/meter³ in the presence of water vapor of about 0.22% or less. 2.The method of claim 1 wherein the coronal-catalyst is a high dielectriccatalyst.
 3. The method of claim 2 wherein the coronal-catalyst is glasswool.
 4. The method of claim 1 further comprising adding suitablequantities of reducing gas to increase NO reduction.
 5. A method ofenvironment effective reducing of NO_(x) emission comprising the step ofreactively exposing NO_(x) to a sulfur tolerant coronal-catalyst infilamentous form wherein said coronal-catalyst is adapted and configuredfor hypercritical presentation to an NO_(x) bearing gas stream whereinsaid exposing occurs at a minimum of at least about 75 watts/meter³ inthe presence of water vapor of about 0.22% or less.
 6. The method ofclaim 5 wherein the coronal-catalyst is a high dielectric catalyst. 7.The method of claim 6 wherein the coronal-catalyst is glass wool.
 8. Themethod of claim 5 further comprising:producing NO_(x) environmenteffective reduction apparatus comprising a sulfur tolerantcoronal-catalyst of glass wool or ceramic-glass wool; disposing saidcoronal-catalyst in from one to a plurality of tubular membersconfigured and adapted to receive a flow of NO_(x) bearing gas;maintaining said coronal-catalyst at an electric power density of atleast about 75 watts/meter³ in the presence of water vapor of about0.22% or less; said coronal-catalyst being present in amounts of fromabout 0.5 to about 150 kg/m³ ; applying to said one to a plurality oftubular members voltage from about 4000 to about 30,000 volts; saidvoltage having a frequency of from 60 Hz to about 30,000 Hz; maintainingresidency of said flow of NO_(x) bearing gas in said tubular members offrom about 0.2 to about 5 seconds or more.
 9. The method of claim 8further comprising applying said voltage by means of a midpoint groundtransformer or a cold cathode transformer.